Spray nozzle for a spray dryer

ABSTRACT

A spray nozzle for use in carrying out a spray-drying process. The spray nozzle comprises an upper part, which is fitted with a plurality of feed pipes supplying a solution to be sprayed and a spray-inducing medium, an axial conpensator, and a base plate, which is made up of rigid but elastic material and connected to two of the said feed pipes and to the axial compensator. The nozzle further comprises an intermediate plate and a nozzle head. The nozzle head has a plurality of passageway-defining rings therein and is secured to the intermediate plate by means of a fastener, and the base plate and intermediate plate are detachably secured together.

[45] Nov. 6, 1973 Hall Z39/397.5

5/1929 Chandler 239/424 X 5/1958 Schoenmokers et al......... Z39/397,5

Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-John J. Love Attorney-Arthur G. Connolly et al.

[57] 'ABSTRACT SPRAY NOZZLE FOR A SPRAY DRYER Inventors: Fritz Mller, Hurth-Knapsack; Robert Queck, Hurth-Burback; Josef Koch; Werner Kowalski, Hurth-Knapsack; Werner Nolden, Bruhl; Gnter Selbst, Hurth- Hermulheim; Helmut Dring, Hurth, all of Germany United States Patent [191 Mller et al. A

PATENTED NDV 6 i975 SHEU 1 DF 2v FIGJ 1 SPRAY NOZZLE FOR A SPRAY DRYER This invention relates to a spray nozzle suitable for use in a spray-drying process.

A spray nozzle. has already been described of which the upper part is made up of three tubular structures of different lengths, which are coaxially assembled so as to form an outer passageway and an inner passageway with an intermediate passageway therebetween. A spray-inducing medium, for example steam or compressed air, is forced through the outer and inner passageways, and a solution or suspension to be sprayed is forced throughthe intermediate passageway, towards the nozzle head. According to German Patent Specification No. 1,667,566, for example, it is necessary for the intermediate annular passageway through which the solution issues to have a width of a fraction of a millimetre, and for the outer and inner annular passageways to have a width of a few millimetres, near the nozzle head.

Owing to the difference between the temperature of the spray-inducing medium and that of the solution or suspension, the individual tubular structures undergo non-uniform expansion. For this reason, and because the temperatures prevailing in the spray tower have to be increased or reduced to give solid products of different physical or chemical properties, the tubular structures defining the individual annular passageways and terminating in the nozzle head are caused to move against each other. This relative movement is undesirable in itself, and it also affects the included angle between the frontal surface areas of the annular passageways and the horizontal, which angle determines the angle of emergence of the issuing spray solution or suspension and hence the throughput in the spray tower.

It may be added here that the nozzles used in spraydrying processes use nozzle heads which normally have a service life between 30 and 200 hours. After that time, the nozzles (those of the prior art, that is) have to be dismantledcompletely and reassembled after replacement of worn components.

lt is an object of the present invention to provide a spray nozzle which is fitted with a readily exchangeable nozzle head and which is so designed as to prevent thermal expansion phenomena from producing relative movement of the tubular structures defining the annular passageways therein (i.e., movement of these structures against each other) and from affecting the included angle between the frontal surface areas of the said annular passageways and the horizontal.

The invention will now be described with reference to the accompanying drawings, in which FIG. l is a side elevational view of a spray nozzle according to the present invention, taken along line I--I of FIG. 2, and

FIG. 2 is atop plan view of the spray nozzle, taken along line II-II of FIG. l.

As can be seen, the spray nozzle comprises four principal parts, namely an upper part 1, a base plate 2, an intermediate plate 3 and a nozzle head 4.

The nozzles upper part 1 is provided with feed pipes 5, 9, l0, 11 and 13 for the supply of a solution to be sprayed and ofa spray-inducing medium. Feed pipe 5, supplying the solution, opens into an extension of an axial compensator 15, which is provided for the purpose of evening out thermal expansion effects.

The nozzle head 4 comprises a plurality of, preferably four, passageway-defining rings 16, I17, 18 and 19, the ring 19 being secured to the intermediate plate 3 by means of a fastener, which in the construction shown comprises a bolt 22 and a bearing disc 23.

The basel plate 2 and intermediate plate 3 are fastened together by means of screws 21 (FIG. 2).

The solution to be sprayed flows through an annular chamber 6 and an intermediate annular passageway 7 into the intermediate passageway 8 lying between rings 17 and 18, and the spray-inducing medium is caused to flow through the inner feed pipe 9 and the outer feed pipes 13, which'are arranged cage-wise, into the inner passageway l2 lying between rings 18 and 19, and through an annular mixing chamber 20 into the outer passageway 14 lying between rings 16 and 17.

Needless to say, the invention is not limited to the exemplifying embodiment shown; thus various modifications may be made without departing from the scope of the invention, which will'now be indicated. f

A spray nozzle according to the present invention comprises an upper part, e.g., as shown at l, which is provided with a feed pipe, e.g., as shown at 5, supplying the solution to be sprayed and with feed pipes, e.g., as shown at 9, 10, l1 and 13, supplying the spray-inducing medium, and with an axial compensator, e.g., as shown at l5; a base plate, e.g., as shown at 2, made up of rigid but elastic material and connected to two of the said feed pipes, which in the nozzle shown in the drawing are the pipes 9 and 13, and to the axial compensator; an intermediate plate, e.g., as shown at 3, and a nozzle head, e.g., as shown at 4, which substantially comprises a purality of passageway-defining rings, e.g., as shown at 16, 17, 18 and 19, and is secured by means of a fastener, e.g., as'shown at 22, to the intermediate plate, the base plate and intermediate plate being detachably secured together.

' Preferred features of the present invention provide:

a. for the angle a, which is included between the imaginary extension of the lower boundary line of the innermost passageway-defining ring 19 and the junction line of the front surface areas of the remaining passageway-defining rings 16, 17 and 18, to be adjustable to a predetermined value, independently of the operational conditions selected;

b. for the angle a to be adjustable to values between 1 and 20, preferably between 2 and 10;

c. for the feed pipes 13 supplying the spray-inducing l medium to be arranged in cage-wise fashion and to be welded to the base plate 2 so as to form the outer boundary line of the nozzles upper part l; d. for the arrangement of an annular mixing chamber 20 downstream of the feed pipes 13 supplying the spray-inducing medium, the mixing chamber extending from the base plate 2 via the intermediate plate 3 to the nozzle head 4.

By the use of a base plate 2 which has a mechanical strength considerably greater than that of the nozzles upper part 1 and which permits non-uniform thermal expansion effects to be evened out, it is possible in the spray nozzle of the present invention effectively to prevent the annular passageways 14, 8 and l2 from widening or narrowing. As a further result of this, the angle a remains unchanged. This angle a must be accurately adhered to, so asto obtain optimum throughput rates in a spray tower, the optimum throughput rate in any given case being dependent upon the geometry of theflame and the ldiameter of the spray tower. (The angle a is shown at the foot of FIG. l of the accompanying drawings).

Parts which normally require replacement in the spray nozzle of the present invention are the passageway-defining rings 16, 17, 18 and 19. Itis therefore particularly advantageous for the spacer or intermediate plate 3 and the nozzle head 4 to be readily detachable from the nozzles upper part 1 and from the base plate 2, by unscrewing the screws 21. This can be done on the spray tower. As soon as a new spacer or intermediate plate 3 and nozzle head 4 have been screwed to the base plate 2, the spray nozzle is ready for operation.

The temperatures prevailing within the inner feed pipe 9 and in the annular chamber 6 or annular passageway 7 may be found to differ by more than 100C, if use is made of steam under a pressure of 15 atmospheres gauge, for example. As a result, the pipes affected by these temperatures are subject to nonuniform thermal expansion which, however, is evened out by means of axial compensator l5.

In order to ensure that the spray-inducing medium will issue uniformly through the outer annular passageway 14, a preferred feature of the invention provides for an annular mixing chamber 20 to be formed, between the base plate 2 and nozzle head 4, within the intermediate plate 3.

The spray nozzle of the present invention can be used for the manufacture of solid salts from their solutions, for example sodium sulfate from an aqueous solution thereof, where it is merely necessary to remove the solvent (commonly water) therefrom. Use can also be made of the present spray nozzle for the manufacture of those salts which are obtained only by the removal of chemically combined water, in addition to solvent water; it can thus be used, for example, for the manufacture of alkali metal polyphosphates from alkali metal orthophosphate solutions.

We claim:

1. A spray nozzle for a spray dryer, the nozzle having an upper part provided with `a feed pipe for the supply of a solution to be sprayed, and with feed pipes for the supply of a spray-inducing means; and a nozzle head comprised of a plurality of ring-shaped members arranged concentrically with respect to each other so as to leave an inner annular passageway, an outer annular passageway and an intermediate annular passageway therebetween, the said nozzle comprising a base plate of hard-elastic and rigid material and an intermediate plate, both positioned between the upper part of the nozzle and the nozzle head and being detachably secured together; a plurality of feed pipes which are parallel with respect to the axis of the nozzle and arranged in a cage formation so as to form the outer boundary line of the upper part of the nozzle, and of which the ends are fast with base plate,-the said feed pipes introducing the spray-inducing medium into the outer annular passageway; inner feed pipe being disposed on the axis of the nozzle and being connected to introduce spray-inducing medium into inner annular passageway, ring-shaped members, forming the nozzle head, being detachably secured to the intermediate plate; a fastener supporting the inner-most ring-shaped member by means of a bearing disc; annular channel disposed about inner feed pipe and connected to supply the solution being sprayed to intermediate annular passageway, an4 inlet conduit being connected to the annular channel, an axial compensator being radially spaced from inner feed pipe and being positioned between the wall of said feed pipe and the inlet conduit on the outer wall of annular channel for the supply of the solution to be sprayed; the spray-inducing means being supplied through the inner annular passageway and the outer annular passageway and the solution to be sprayed being supplied through the intermediate annular passageway in the nozzle head.

2. The spray nozzle as claimed in claim 1, wherein an angle a, is included between the imaginary extension of the lower boundary line of the innermost ring-shaped member and the junction line of the frontal surface areas of the other ring-shaped members, and the angle a is adjustable to a predetermined value.

3. The spray nozzle as claimed in claim 2, wherein the angle a is adjustable to values between 1 and 20.

4. The spray nozzle as claimed in claim 3, wherein the angle a is adjustable to values between 2 and 10.

5. The spray nozzle as claimed in claim 1 wherein annular channel has a closed rear end remote from interchannel.

ll ll 

1. A spray nozzle for a spray dryer, the nozzle having an upper part provided with a feed pipe for the supply of a solution to be sprayed, and with feed pipes for the supply of a spray-inducing means; and a nozzle head comprised of a plurality of ring-shaped members arranged concentrically with respect to each other so as to leave an inner annular passageway, an outer annular passageway and an intermediate annular passageway therebetween, the said nozzle comprising a base plate of hard-elastic and rigid material and an intermediate plate, both positioned between the upper part of the nozzle and the nozzle head and being detachably secured together; a plurality of feed pipes which are parallel with respect to the axis of the nozzle and arranged in a cage formation so as to form the outer boundary line of the upper part of the nozzle, and of which the ends are fast with base plate, the said feed pipes introducing the spray-inducing medium into the outer annular passageway; inner feed pipe being disposed on the axis of the nozzle and being connected to introduce sprayinducing medium into inner annular passageway, ring-shaped members, forming the nozzle head, being detachably secured to the intermediate plate; a fastener supporting the inner-most ringshaped member by means of a bearing disc; annular channel disposed about inner feed pipe and connected to supply the solution being sprayed to intermediate annular passageway, an inlet conduit being connected to the annular channel, an axial compensator being radially spaced from inner feed pipe and being positioned between the wall of said feed pipe and the inlet conduit on the outer wall of annular channel for the supply of the solution to be sprayed; the spray-inducing means being supplied Through the inner annular passageway and the outer annular passageway and the solution to be sprayed being supplied through the intermediate annular passageway in the nozzle head.
 2. The spray nozzle as claimed in claim 1, wherein an angle Alpha , is included between the imaginary extension of the lower boundary line of the innermost ring-shaped member and the junction line of the frontal surface areas of the other ring-shaped members, and the angle Alpha is adjustable to a predetermined value.
 3. The spray nozzle as claimed in claim 2, wherein the angle Alpha is adjustable to values between 1* and 20*.
 4. The spray nozzle as claimed in claim 3, wherein the angle Alpha is adjustable to values between 2* and 10*.
 5. The spray nozzle as claimed in claim 1 wherein annular channel has a closed rear end remote from intermediate annular passageway, and said closed rear end having a radially extended bulbous wall to comprise said axial compensator and make it capable of absorbing axial expansion of the wall of the annular channel.
 6. The spray nozzle as claimed in claim 1, wherein the front end of annular channel adjacent intermediate annular passageway is secured to base plate.
 7. The spray nozzle as claimed in claim 1, wherein the cage of feed pipes is freely disposed about annular channel. 